Anderson Dennis E, Madigan Michael L
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, and with the Department of Orthopedic Surgery, Harvard Medical School, Boston, MA.
J Appl Biomech. 2013 Oct;29(5):505-16. doi: 10.1123/jab.29.5.505. Epub 2012 Nov 21.
Maintenance of healthy bone mineral density (BMD) is important for preventing fractures in older adults. Strains experienced by bone in vivo stimulate remodeling processes, which can increase or decrease BMD. However, there has been little study of age differences in bone strains. This study examined the relative contributions of age-related differences in femoral loading and BMD to age-related differences in femoral strains during walking using gait analysis, static optimization, and finite element modeling. Strains in older adult models were similar or larger than in young adult models. Reduced BMD increased strains in a fairly uniform manner, whereas older adult loading increased strains in early stance but decreased strains in late stance. Peak ground reaction forces, hip joint contact forces, and hip flexor forces were lower in older adults in late stance phase, and this helped older adults maintain strains similar to those of young adults despite lower BMD. Because walking likely represents a "baseline" level of stimulus for bone remodeling processes, increased strains during walking in older adults might indicate the extent of age-related impairment in bone remodeling processes. Such a measure might be clinically useful if it could be accurately determined with age-appropriate patient-specific loading, geometry, and BMD.
维持健康的骨矿物质密度（BMD）对于预防老年人骨折至关重要。骨骼在体内所承受的应变会刺激重塑过程，这可能会增加或降低骨矿物质密度。然而，关于骨应变的年龄差异的研究很少。本研究使用步态分析、静态优化和有限元建模，研究了与年龄相关的股骨负荷差异和骨矿物质密度差异对步行过程中股骨应变的年龄差异的相对贡献。老年人模型中的应变与年轻人模型中的应变相似或更大。骨矿物质密度降低以相当均匀的方式增加应变，而老年人的负荷在站立初期增加应变，但在站立后期降低应变。在站立后期阶段，老年人的地面峰值反作用力、髋关节接触力和髋部屈肌力量较低，这有助于老年人尽管骨矿物质密度较低，但仍能保持与年轻人相似的应变。由于步行可能代表了骨骼重塑过程的“基线”刺激水平，老年人步行过程中增加的应变可能表明骨骼重塑过程中与年龄相关的损伤程度。如果能够通过适合年龄的患者特异性负荷、几何形状和骨矿物质密度准确确定这种测量方法，那么它可能在临床上有用。
